Water samples collected for the determination of selected radionuclides.

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The impact of recent releases from the Fukushima nuclear accident on the marine environment (FRAME)

This collaboration of scientists from Spain, US, Belgium, Switzerland and Japan aim to better understand the sources, fate, transport, bioaccumulation and associated impact of radionuclides from the Fukushima Dai-ichi NPP accident in Japan. The investigation encompasses the main compartments of a complex marine environment, namely the water column, the seafloor and marine biota living within them. We investigate coastal and offshore sites, participating in several oceanographic cruises in 2014, 2015 and 2016 in the most heavily impacted areas identified in our previous studies and allowing a time-series of the changing contamination levels.

We will determine the concentrations of a suite of contaminant radionuclides (137Cs, 134Cs, 90Sr, plutonium isotopes, 236U and 129I) in water, suspended matter and bottom sediments, and we will assess the transfer to marine biota (including fish, macroalgae and plankton). This will be accompanied by measurements of other natural radionuclides (i.e. 234Th, 210Pb, Ra isotopes) in order to quantify groundwater fluxes, residence times in the ocean and accumulation and mixing rates in bottom sediments.

The work shall be instrumental in addressing relevant questions such as: i) Which is the fate of the contamination in the ocean, what fraction of the total releases is stored in marine sediments and what is the aerial extent of the contamination in the seafloor; ii) How much radioactivity is still leaking from the Fukushima Dai-ichi site and which are the mechanisms that govern the releases to the ocean, such as the role of submarine groundwater discharge; iii) To which extent have the concentrations of contaminants in the ocean changed since 2011; and iv) What are the current impacts on marine biota.